1. Field of the Invention
This invention relates to the field of rope and cable. More specifically, the invention comprises a method for potting cable terminations, along with devices for carrying out the method.
2. Description of the Related Art
Devices for mounting a termination on the end of a rope or cable are disclosed in detail in copending U.S. application Ser. No. 60/404,973 to Campbell, which is incorporated herein by reference. Generally, the strands proximate the end of a cable are wetted with a potting compound to affix them to an anchor (The term “anchor” is used to refer generally to any object affixed to a cable in order to transmit a load to or from the cable).
FIG. 1 shows a cable 10 ready for the application of a potting process. Those skilled in the art will know that a cable is generally composed of a bundle of smaller strands. Over most of its length, the strands within cable 10 will generally be held in place by a containment jacket 12 (which may be an extruded plastic jacket, a braided strand jacket, or similar encircling sheath). In other cases, no encircling jacket will be present. For these, a tape sheath or other compressing method such as a string wrap must be used to organize the strands for potting. However it is done, a length of strands must be exposed for potting (meaning that they can be infused with potting resin). In the view, these are designated as exposed strands 14.
In order to lock the cable to an anchor, exposed strands 14 must be wetted with a potting compound. This is typically done in one of two ways: (1) An anchor is pulled around the exposed strands to hold them in place while a potting compound is poured into them, or (2) The exposed strands are wetted and then an anchor is pulled over the exposed strands to form them into the proper shape. FIG. 2 shows a completed termination, with anchor 40 being locked to potted region 22.
However the potting compound is applied, there will be a transition between the unpotted strands and the potted strands. This is referenced as potting transition 20 in the figure. The reader will note that potting transition 20 is irregular. It is difficult for the potting compound to penetrate to the center of the cable. Even though the strands are splayed prior to potting, those strands near the center tend to remain bunched together, inhibiting the penetration of the liquid potting resin (designated as central strand region 16). The bunching lessens toward the periphery of the cable and in the vicinity of the end of the cable (designated as end strand region 18). Because of this variation in strand density, uneven penetration of the potting compound often results. This fact introduces inconsistency from assembly to assembly, since the location and shape of potting transition 20 varies significantly. When attempting to pre-wet the strands, the center strands also tend to be guarded somewhat by the cable itself. Consistency in the application of the potting compound therefore suffers.
Throughout this disclosure, the term “strand” will be used to describe the constituents of synthetic cables, natural-fiber cables, and wire ropes. Although synthetic cables are used for the illustrations, the reader should understand that the methods and devices disclosed are equally applicable to any type of stranded cable.